I have a build that failed, and then failed again 24 hours later (I assume). It has been a few days and believe we addressed the build issue. Will a build automatically re-trigger or is there a way to manually kickoff another build?

Currently DepShield will only process commits where it can tell if the dependencies or build have changed in some way. So if you make a change to your build file (e.g. pom.xml, package.json, etc…) then it should get picked up by DepShield.